Technical Abstract:
Mycosphaerella is one of the largest genera of plant pathogenic fungi with more than 1,000 named species, a few of which cause disease in humans and other vertebrates. The genomes of M. graminicola and M. fijiensis, two of the most economically important pathogens of wheat and banana, respectively, were sequenced plus 40,000 ESTs from M. fijiensis and the related maize pathogen Cercospora zeae-maydis. The 9x M. graminicola draft sequence was made public November 1, 2006, and the genome is being finished currently. Most chromosomes have been sequenced completely including both telomeres. These data indicate that M. graminicola has both the largest number and the smallest sizes of chromosomes recorded among filamentous ascomycetes. Detailed analyses of progeny isolates showed that a significant number of chromosomes can be missed and potentially contain redundant information for pathogenicity and mating. The repetitive content of the individual chromosomes is significantly but disproportionately larger on the <2Mb chromosomes indicating that at least some may be considered supernumerary. Major factors for pathogenicity are located on the larger chromosomes and mostly towards the telomeres. More than 1200 genes have been annotated manually and indicate that this pathogen contains smaller gene families compared to other well studied filamentous plant pathogenic fungi, which may reflect its incognito life style. The M. fijiensis EST project generated more than 30,000 sequences and the genome sequencing resulted in an approximately 70Mb genome size that contains a substantial amount of repetitions. Interestingly, the genome sequence showed a double CG-peak that is absent in the M. graminicola genome and appears to be specific for Mycosphaerella pathogens of banana.